python3 使用urllib报错urlopen error EOF occurred in violation of protocol (_ssl.c:841)

python3源码：

import urllib.request
from bs4 import BeautifulSoup

response = urllib.request.urlopen("http://php.net/")
html = response.read()
soup=BeautifulSoup(html, "html5lib")
text=soup.get_text(strip=True)
print(text)

　　代码很简单，就是抓取http://php.net/页面文本内容，而后使用BeautifulSoup模块清除过滤掉多余的html标签。貌似第一次容许成功了，以后一直卡着再报错：

File "C:\Python36\lib\urllib\request.py", line 504, in _call_chain
    result = func(*args)
  File "C:\Python36\lib\urllib\request.py", line 1361, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "C:\Python36\lib\urllib\request.py", line 1320, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error EOF occurred in violation of protocol (_ssl.c:841)>

　　实际上google浏览器是可以访问的。

　　此问题多是因为Web服务器上禁用了SSLv2，而比较老的python库Python 2.x尝试默认状况下与PROTOCOL_SSLv23创建链接。所以在这种状况下，须要选择请求使用的SSL版本。

　　要更改HTTPS中使用的SSL版本，须要将该HTTPAdapter类子类化并将其挂载到 Session对象。例如，若是想强制使用TLSv1，则新的传输适配器将以下所示：

from requests.adapters import HTTPAdapter from requests.packages.urllib3.poolmanager import PoolManager class MyAdapter(HTTPAdapter): def init_poolmanager(self, connections, maxsize, block=False): self.poolmanager = PoolManager(num_pools=connections, maxsize=maxsize, block=block, ssl_version=ssl.PROTOCOL_TLSv1)

　　而后，能够将其挂载到Requests Session对象：

s=requests.Session() s.mount('https://', MyAdapter()) response = urllib.request.urlopen("http://php.net/")

　　编写一个通用传输适配器仍是很简单，它能够从ssl构造函数中的包中获取任意SSL类型并使用它。

from requests.adapters import HTTPAdapter from requests.packages.urllib3.poolmanager import PoolManager class SSLAdapter(HTTPAdapter): '''An HTTPS Transport Adapter that uses an arbitrary SSL version.'''
    def __init__(self, ssl_version=None, **kwargs): self.ssl_version = ssl_version super(SSLAdapter, self).__init__(**kwargs) def init_poolmanager(self, connections, maxsize, block=False): self.poolmanager = PoolManager(num_pools=connections, maxsize=maxsize, block=block, ssl_version=self.ssl_version)

　　修改后的上述出错的代码：

import urllib.request from bs4 import BeautifulSoup import requests from requests.adapters import HTTPAdapter from requests.packages.urllib3.poolmanager import PoolManager import ssl class MyAdapter(HTTPAdapter): def init_poolmanager(self, connections, maxsize, block=False): self.poolmanager = PoolManager(num_pools=connections, maxsize=maxsize, block=block, ssl_version=ssl.PROTOCOL_TLSv1) s=requests.Session() s.mount('https://', MyAdapter()) response = urllib.request.urlopen("http://php.net/") html = response.read() soup=BeautifulSoup(html, "html5lib") text=soup.get_text(strip=True) print(text)

　　能够正常抓取网页文本信息。